1. Field of the Invention
The present invention is directed to inkjet printers, and more specifically to devices and methods for detecting the presence of gaseous impediments within ink conduits that might impair the flow of ink between an ink source and nozzles of a printhead.
2. Background of the Invention
Inkjet printers include at least one printhead having numerous nozzles through which ink is ejected in the form of droplets that are preferably deposited onto a printable medium. The precise and accurate deposition of droplets form image-based, dielectric, and/or conductive representations. In order to deposit ink onto the printable medium, the printhead includes numerous electric resistors that are selectively “fired”. A resistor is “fired” by directing electric current therethrough to generate thermal energy sufficient to vaporize a fraction of liquid ink in thermal communication with the resistor, thereby generating a vapor bubble that forces a droplet of liquid ink from the nozzle. The resistor firing sequence occurs numerous times a second and is coordinated with the movement of the nozzles across the printable medium by associated controls of the printer.
An electronic version of the representation to be printed is commonly referred to as a bit map. A bit map includes instructions regarding the position of the nozzles in order to deposit ink in predetermined locations on the print medium. This means that at least one of the nozzles and the print medium must be repositionable. An exemplary manner of repositioning the print medium with respect to the nozzles may include moving the print medium vertically and moving the nozzles horizontally along a reel to cover the relevant areas of an imaginary X-Y plane. The operation of a reel and movement of the printhead in accordance with the instructions of the bit map are well known by those of ordinary skill.